Coating steel



Patented May 28, 1940 PATENT OFFICE COATING STEEL Vincent T. Malcolm, Indian Orchard, Mass., as-

signor to The Chapman Valve Manufacturing (70., Indian Orchard, Mass., a corporation of Massachusetts No Drawing. Application July 12, 1939, Serial No. 284,091

2 Claims. (01. 14s- -c.5)

-This invention. relates to improvements in steels and is directed more particularly in methods of treating or coating steels to provide a protective coating thereforr 5 The principal objects of the invention pertain to a method of treating steels such as ordinary austenitic carbon and alloy steels in such a way as to provide a protective coating 'having characteristics rendering the same generally resistant to corrosion.

According to the invention in its broad aspects the steel to be treated or coated is immersed in a solution having novel characteristics and subjected to heating temperatures for a length of time.

The solution according to the invention in.- cludes electrolytic sodium hydroxide, sulphur and phosphoric acid, previous to which the steel is cleaned or degreased.

As an example the steel may be cleaned or de greased in carbon tetrachloride. Other cleaning substances or compounds may be used but in order to obtain the desired results the cleaning must be reasonably thorough.

26 The solution according to the invention may be as follows:

. Grams Electrolytic sodium hydroxide 100 Water 100 80 Powdered sulphur 1 Phosphoric acid 5 As one example of what has been done, a piece of steel -2- long, 1" wide and 4" thick was soaked inthe coating solution for approximately one-half hour withthe temperature of the solutionin the neighborhood of 270 F.

I The result was a coating which was substantially black and which impregnated the surface of the steel to a marked extent. The coating taken on by the steel had a thickness of from .001" to .003 and had very desirable corrosionresisting qualities in respect to mineral and organic acids as well as the basic solutions.

As instances the coating was resistant to the standard solutions of 4% sodium chloride, magnesium chloride, and salt spray solutions when exposed for a '72 hour period to a spray thereof.

The color of the coating is very pleasing and not at all objectionable. It isreadily and easily applied without the necessity for expensive equipment or materials so that the cost ofcoating is 20 very low. 1

Having thus described my invention, and the best manner of practicing the new process of forming this novel composition, but without limiting myself to the order of steps of such process recited,.or the proportions of parts employed therein, or to the precise ingredients named, asit is evident that each of these ingredients has a considerable range of equivalents and that the order and proportions of the process may be 

